Don't wait till 38: Freezing your eggs late is not as simple or successful

Women who have not yet gotten married – very often religiously observant ones – or found a partner or girls who had cancer and had to undergo chemotherapy that can kill off their eggs – have high hopes of eventually getting pregnant. However, a meta-analysis of the efficiency of egg freezing has found that it decreases significantly if the eggs are frozen at a more advanced age.

According to the new study led by physicians at the in-vitro (IVF) unit at Jerusalem’s Shaare Zedek Medical Center (SZMC), one of two women who froze eggs at an age younger than 35 gave birth using them; and one of three women who froze eggs at the age of nine to 36 years gave succeeded in having a baby. However, only about one if five women who froze eggs at the age of 40 and over gave birth with their help.

As SZMC is a medical center run according to Jewish law, it is natural that observant Jewish women turn to its IVF unit to get their ova frozen and to use them to try to get pregnant. 

Up to age 35

The clear and recommended conclusion of their research that encompasses all the information available in the world today is that it’s better to perform egg freezing before the age of 35. Often, women without a partner who feel the “clock is ticking” have their eggs frozen (at their own expense) in their late 30s.

The study, published in the prestigious journal Human Reproduction Update under the title “Planned oocyte cryopreservation: a systematic review and meta-regression analysis” was led by Dr. Avi Tsafrir and Dr. Ayala Hirsch from SZMC’s IVF unit together with Dr. Bruria Hirsch-Raccah from the School of Pharmacy of the Hadassah Medical Organization. 

In the study, the researchers gathered all the studies in the world that reported on women who froze eggs for the purpose of fertility preservation and later used them. The researchers found 10 studies that together included 8,750 women who froze eggs for the purpose of preserving fertility. Of these, about 1,500 (only 11% of all those who froze) returned to treatment with the aim of conceiving with the help of these eggs. The authors learned that the average age at which women freeze eggs was 38. 

In developed nations, women are increasingly delaying pregnancy. After reaching their mid-30s, female fertility demonstrates a notable decline as age progresses, eventually resulting in age-related infertility. Due to their large size, high water content, and unique intracellular structure, oocytes are particularly sensitive to cooling and prone to cryoinjuries The first successful birth from a frozen oocyte was reported in 1986, using the slow freezing technique. However, despite this early breakthrough, the widespread adoption of oocyte cryopreservation was hindered by poor survival rates of frozen eggs. 

A significant advancement came with the introduction of vitrification, which involves a solidification process in which the oocytes are treated with cryoprotective substances and submerged in liquid nitrogen at a temperature of -196°C. The steps are the same as in an IVF cycle: stimulation of the ovary with hormones followed by aspiration of the oocytes. This method was proven to be safe in terms of birth outcomes, and, in comparison with slow freezing, vitrification was significantly superior to slow freezing for oocyte survival. 

Tsafrir wrote that since relatively few women out of the many who froze eggs actually returned to use them, the information regarding the effectiveness of the process is limited. Today, many women froze eggs for personal reasons. “Therefore, the collection of data for the first time from all over the world gives us well-founded conclusions and indications for important recommendations regarding the recommended age for egg retrieval.”

Prof. Ido Ben Ami who heads SZMC’s IVF unit concluded that “in recent years, we have seen an increase in the number of women who request egg freezing for personal reasons in all sectors, and we definitely see greater success rates in women who froze at a relatively early age. So this important and comprehensive study is an international reference for recommendations are important on this subject, and I am sure that his conclusions and recommendations will be implemented in all IVF units here and abroad.”